Code Barn Hello Server File   

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Explanation of HelloServerFile applet

Number of files: 2 (HelloServerFile.class, and a text file named test.txt)

What it does: Gets the text from a text file on the server and displays each line from the text file on the screen. Applets can't actually *read* from the server, but the URL class allows an applet to GET text from a URL.

To GET text from a URL:

1. Create a URL object which represents the URL of the text file
2. Get an InputStream on that URL
3. Read from the Stream

HelloServerFile does a very simple readLine on a JavaDoc:java.lang.BufferedReader .

To display the text from the text file, HelloServerFile creates a unique Label object to display each line of text. This is just for an example of a way to dynamically generate components based on information in a text file. At compile-time, there was no way to know how many Labels would be needed.


import java.applet.Applet;
import java.awt.FlowLayout;
import java.awt.Label;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

public class HelloServerFile extends Applet 
{

    public void init() 
    {
        // everything happens in init
        setLayout( new FlowLayout( FlowLayout.CENTER, 1000, 5 ) );
        String line = null;

        try
        {
            // create a URL (the URL for the text file on the server) then open a stream
            URL textURL = new URL( getCodeBase() , "test.txt" ); 
            BufferedReader reader = new BufferedReader( new InputStreamReader( textURL.openStream() ) );
    
            // now read the lines one at a time 
            while ( ( line = reader.readLine() ) != null ) 
            {
                add( new Label( line ) );
            } // close while loop
    
            reader.close();
        } // close try
        catch ( Exception e ) 
        {
            e.printStackTrace();
        } 
    } // close init
} // close applet